The FLAG peptide is a hydrophilic sequence composed of 8 amino acids (DYKDDDDK), commonly used for the detection of specific anti-FLAG monoclonal antibodies. To enhance detection sensitivity, a 3×FLAG version—known as the 3×FLAG-tag peptide—was developed. This extended tag consists of 23 amino acids and enables the detection of fusion proteins at levels as low as 10 femtomoles. The 3×FLAG-tag peptide is widely utilized for the purification of FLAG-tagged fusion proteins and for competitive binding to anti-FLAG monoclonal antibodies. The recommended working concentration for the 3×FLAG-tag peptide ranges from 100 to 400 μg/mL.
